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best ccna 200 301 book.Figure 9-9 EIGRP Complete Routing Update and Partial Routing UpdateNote that EIGRP considers the information exchanged in the update to be topology information. This information is not as detailed as the OSPFLS topology data, which does not depict every router and link in the network. However, its depiction of local routers is not limited to distance (metric) and vector (next-hop router) a local router is also very aware of the metric used by the next-hop router. This additional information is used to help EIGRP converge quickly without loopbacks, a topic that will be discussed in the subsequent "EIGRP Convergence" section.3. Calculating the Best Route in the Routing TableEIGRP calculates routes using a different metric than any other routing protocol. For example, in OSPF, the OSPF metric (overhead) can be calculated accurately for each path as long as the network diagram is available and the configured OSPF interface overhead is known.EIGRP uses mathematical equations and composite metrics, making the metric values very difficult to predict. Calculation of the EIGRP MetricThe EIGRP composite metric means that EIGRP injects multiple inputs (called "metric components") into the mathematical equation. By default, EIGRP injects two metric components into the calculation: bandwidth and latency. (EIGRP also supports the use of interface load and interface reliability in metric calculations, although Cisco does not recommend the use of either o) EIGRP also advertises the maximum transmission unit (MTU) bound to a route, which is the longest IP packet allowed on that route, but does not apply the MTU in metric calculations.Hint: Previous literature and books often state that EIGRP, and its predecessor IGRP, can also use MTU as part of the metric, but in practice MTU cannot be used and can never be used as part of that calculation. .EIGRP's formula for calculating metric values actually helps describe some key points about metric values. This formula assumes the default settings of using only bandwidth and latency, as follows.Metric Value = ------------------------- + Cumulative Latency X256 Minimum Bandwidth / /3.2 Base Content 197In this formula, the term Least-Bandwidth refers to the smallest bandwidth link in a route, measured in kilobits per second. For example, if the slowest link to a route is a 10Mbit/s Ethernet link, then the first part of the formula is 10710 4,which is equal to 1000. here IO, is used in the formula because 10Mbit/s is equal to 10000kbit/s (10'kbit/s).